Implantable orthopedic prostheses to replace human bone joint interfaces are well-known. In particular, it is known to implant a prosthesis on a resected proximal surface of the tibia to articulate with a femoral knee prosthesis. Such prostheses are known, for example, from U.S. Pat. Nos. 4,963,152; 5,062,852; and 5,071,438, assigned to Intermedics Orthopedics, Inc. the assignee of my present invention. Tibial prosthesis frequently comprise a metal baseplate having some form of fixation means to attach the baseplate to the resected surface of the tibia. Such means may include bone screws, pegs, or medullar shafts. Medullar shafts of cruciate shape are also known. On the metal baseplate is attached an articulating surface, frequently made of ultra high molecular weight polyethylene (UHMWPE). In addition, all-polyethylene tibial prostheses have been proposed. Prosthesis with metal baseplates are somewhat complex and expensive to manufacture. On the other hand, all-polyethylene tibial prostheses tend to lack stiffness.
With the foregoing in mind, it has been an object of my invention to provide a tibial prosthesis wherein both the articulating surface and the fixation means were of a common polyethylene part, but which was provided with a metal interface at the proximal end of the tibia.
It has also been an object of my invention to provide such a prosthesis which could be easily assembled. A further object of my invention has been to provide a two-part prostheses which could be easily manufactured.
These and other objects and features of my invention will be apparent from the following description taken with reference to the accompanying drawings.